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Urea Transformations in Flooded Soil Columns: II. Derivation of Model and Implications to Ammonia Volatilization
Author(s) -
Bouldin D. R.,
Hongprayoon C.,
Patrick W. H.,
Lindau C. W.
Publication year - 1991
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1991.03615995005500040039x
Subject(s) - ammonia volatilization from urea , urea , volatilisation , chemistry , hydrolysis , ammonia , soil water , fertilizer , environmental chemistry , diffusion , hydrology (agriculture) , environmental science , soil science , biochemistry , geology , organic chemistry , geotechnical engineering , physics , thermodynamics
Ammonia volatilization from rice ( Oryza sativa L.) paddies following urea application reduces the effectiveness of the urea‐N. The objectives of this study were to: (i) derive, for flooded soils, a model describing hydrolysis and diffusion of urea and diffusion of ammoniacal N; (ii) derive the necessary parameters from experimental data, and (iii) use the model to study implications of hydrolysis/transport parameters and management variables to NH 3 volatilization. The parameters are diffusion coefficients of urea and NH 4 in soil, hydrolysis coefficients of urea in the soil and overlying floodwater, and the sorption coefficient for NH 4 on the soil. The effects on potential for NH 3 volatilization of variation in these parameters and the management factors of depth of flood water and depth of fertilizer incorporation were calculated. The results illustrate that urea‐hydrolysis rates in the floodwater and soil are the most important factors influencing the potential for NH 3 volatilization. If urea‐hydrolysis rates are very high, incorporation and shallow floodwater are the indicated management while, with low hydrolysis rates, deep floodwater and no incorporation are the indicated management.